Single PSA Test May Reveal Long-Term Prostate-Cancer Risk

Baseline prostate-specific antigen (PSA) levels in midlife are associated with the subsequent risk of clinically significant prostate cancer, according to a secondary analysis of a large clinical trial.

As Dr. Evan Kovac told Reuters Health by email, "Our study of over 10,000 younger men (aged 55-60) enrolled in the Prostate, Lung, Colorectal and Ovarian (PLCO) randomized screening trial found that a single PSA blood test, taken in mid-life, predicts the long-term diagnosis of important prostate cancer."

In a paper in JAMA Network Open, Dr. Kovac of Montefiore Medical Center, in New York City, and colleagues note that, "While PSA screening was once widely accepted and ubiquitous, opinions on the utility of screening have shifted in recent years, and there is now controversy surrounding its use as a screening tool because of the overdiagnosis and overtreatment of indolent cancers."

The researchers examined data from the PLCO trial involving more than 76,000 men aged 55 to 74 years. Their analysis was limited to the nearly 11,000 patients aged 55 to 60 years at study enrollment between 1993 to 2001. All had received at least one PSA test.

The team found that the actuarial 13-year incidence of clinically significant prostate cancer diagnosis among participants with a baseline PSA of 0.49 ng/mL or less was 0.4%. The proportion rose to 1.5% at 0.50-0.99 ng/mL, 5.4% at 1.00-1.99 ng/mL, 10.6% at 2.00-2.99 ng/mL and continued to rise reaching 29.5% at 4.00 ng/mL and greater

There were only 15 prostate-cancer-specific deaths during follow-up, and nine were in men with a baseline PSA level of 2.00 ng/mL or more.

"This study suggests that men aged 55-60 with a PSA less than 1 may consider cessation of further screening as their long-term risk of lethal prostate cancer is very low (around 1%). This strategy could help reduce the potential harms of screening, including the overdiagnosis and overtreatment of non-lethal prostate cancers," concluded Dr. Kovac.

Dr. Philipp Dahm, a professor of urology and vice chair of Veterans Affairs at the University of Minnesota, in Minneapolis, told Reuters Health by email that "this US-based study provides further support for the notion that baseline PSA levels can be used to stratify risk for developing clinically significant prostate cancer."

Dr. Dahn, who has authored several systematic reviews on the effectiveness of prostate-cancer (PCA) screening but was not involved in the new work, added, "It can help support PCA screening de-implementation initiatives (extended screening intervals, stopping altogether) in men with low PSA levels; even those that are relatively young."

A striking finding of the study, he concluded, "is how much higher the risk of dying from other competing causes is (893 men) vs those that died of prostate cancer (15 men); this is one of the fundamental issues related to PCA screening."
—David Douglas



Source